Okay, so I'm going to ignore the difference between Rosharan years and Earth years because as Rai has pointed out, human characters always act like the age they are given. That being said, I think Kaladin+Venli still won't work out, at least not for long. The two mature at different rate, and at some point, the gap would have been too great. I also believe many human (including Kaladin himself) would find Kaladin dating a 14-year-old to be inappropriate, even if Venli doesn't feel that young. And hiding her age also wouldn't work.
The ship might still work out, they might find a way to deal with it all, but I think it's unlikely.